Referring to FIG. 1, a conventional H4-type halogen lamp 1 is installed in a reflecting cover (not shown). The conventional H4-type halogen lamp 1 includes abase seat 11, a transparent cover 12 disposed in front of the base seat 11 and defining an isolated space 121, and a light emitting unit 13 disposed in the isolated space 121. The light emitting unit 13 includes a low beam light module 131 formed by a tungsten filament, a light shield 133 covering a portion of the low beam light module 131, and a high beam light module 132 formed by a tungsten filament.
The low beam light module 131 and the high beam light module 132 are spaced apart from each other in a front-rear direction, and each of the low beam light module 131 and the high beam light module 132 can be individually switched on. Moreover, with the reflecting cover and the light shield 133, each of the low beam light module 131 and the high beam light module 132 can emit light that has specific shape. However, the emitting unit 13 made of tungsten filament may easily burn out due to high temperature after long term use, thereby resulting in a high power consumption and a short service life of the conventional lamp 1.